Feedback: /remind_me quick action

In !149938 (merged) we shipped a proof-of-concept change implementing /remind_me, a feature long requested by the community. We intend to enable this for gitlab-org/gitlab via the feature flag remind_me_quick_action.

The goal of this issue is to gather feedback from team members ("dog fooding") and community members who use this PoC. We hope to learn what ideas, complaints, and next steps should be before opening up the feature to GA, and any inspiration for future features that might be built off this.